I used to use my first name on games until I played Harvest Moon on the SNES and when you were asked to input a name there was a maximum of four letters, which meant my name wouldn't fit.
I picked a letter which sounded like a name and doubled it up. -> JJ
Unfortunately, JJ was too short and generic to use online.
I changed my username to JJ Cool and all was well.
Until I realised there was a music artist named LL Cool J and the similarity caused me to change it again to JJ Kewl.
At some point, I remembered I wasn't 12 anymore and sought out a new name.
The word "Unbreakable" reflects my philosophy in life, as well as my attitude towards clean programming code (C++ ftw), the fact that I haven't broken a single bone in my body, Taoist beliefs ('To win without fighting is best' - Sun Tzu: The Art of War) and a Bruce Willis movie where he doesn't get hurt or sick.